doc: add info about serializable types

querystring.stringify() doesn't serialize some values. Explicitly mention what values are serialized in the docs. Add what happens when another data type is passed to `querystring.stringify()` besides the ones that can be correctly parsed PR-URL: #12313 Reviewed-By: Luigi Pinca <[email protected]> Reviewed-By: Anna Henningsen <[email protected]> Reviewed-By: James M Snell <[email protected]>

Author: shubheksha

doc/api/querystring.md

@@ -98,6 +98,10 @@ added: v0.1.25
 The `querystring.stringify()` method produces a URL query string from a
 given `obj` by iterating through the object's "own properties".
 
+It serializes the following types of values passed in `obj`:
+{string|number|boolean|string[]|number[]|boolean[]}
+Any other input values will be coerced to empty strings.
+
 For example:
 
 ```js